Abstract

A technique for regrowing layers has been developed to realize nonalloyed Ohmic contacts using plasma assisted molecular beam epitaxy. The contact resistance and device performance were measured of a recessed-gate with the regrowth and of recessed-source/drain high electron mobility transistors(HEMTs). With the regrown layers and recessed drain/source, a low contact resistance of was obtained for contacts to AlGaN. The peak drain current and maximum transconductance of the HEMTs with nonalloyed Ohmic contacts were and , respectively. These results demonstrate that the regrowth of highly dopedGaN layers is crucial in achieving low-resistance nonalloyed Ohmic contacts for the HEMT structures.

This work was supported in part by the Research Board and Grainger Center for Electric Machinery and Electromechanics of the University of Illinois and Northrop-Grumman Space Technologies. The microanalysis was carried out in the Center for Microanalysis of Materials of the University which is partially supported by the U.S. Department of Energy under Grant No. DEF02-91-ER45439. Assistance of Dane Sievers in the measurement and of D. Kim in the device fabrication are gratefully acknowledged.